irqchip: Plug a OF node reference leak in platform_irqchip_probe()

platform_irqchip_probe() leaks a OF node when irq_init_cb() fails. Fix it
by declaring par_np with the __free(device_node) cleanup construct.

This bug was found by an experimental static analysis tool that I am
developing.

Fixes: f8410e6 ("irqchip: Add IRQCHIP_PLATFORM_DRIVER_BEGIN/END and IRQCHIP_MATCH helper macros")
Signed-off-by: Joe Hattori <joe@pf.is.s.u-tokyo.ac.jp>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20241215033945.3414223-1-joe@pf.is.s.u-tokyo.ac.jp

Author: joehattori

drivers/irqchip/irqchip.c

@@ -35,11 +35,10 @@ void __init irqchip_init(void)
 int platform_irqchip_probe(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
-	struct device_node *par_np = of_irq_find_parent(np);
+	struct device_node *par_np __free(device_node) = of_irq_find_parent(np);
 	of_irq_init_cb_t irq_init_cb = of_device_get_match_data(&pdev->dev);
 
 	if (!irq_init_cb) {
-		of_node_put(par_np);
 		return -EINVAL;
 	}
 
@@ -55,7 +54,6 @@ int platform_irqchip_probe(struct platform_device *pdev)
 	 * interrupt controller can check for specific domains as necessary.
 	 */
 	if (par_np && !irq_find_matching_host(par_np, DOMAIN_BUS_ANY)) {
-		of_node_put(par_np);
 		return -EPROBE_DEFER;
 	}